Thread: Assignment HELP!!

Code:

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define MAXLEN 200
    
struct integer* read_integer(char* stringInt);
void print(struct integer *p);
struct integer* add(struct integer *p, struct integer *q);
struct integer* subtract(struct integer *p, struct integer *q);
int compare(struct integer *p, struct integer *q);

struct integer{
    int *digits;
    int size;
};

int main(void){
    int numlines; //Number of lines stored in the file
    char string1[MAXLEN];
    char string2[MAXLEN];
    int i;// loop index
    int opr; //Operator 1 or 2 tells us if we add or subtract
    struct integer *p;
    struct integer *q;
    struct integer *answer;

    // Open the file and read from bigint.txt
    FILE *fin;
    fin = fopen("bigint.txt","r");
    fscanf(fin, "%d", &numlines); //Read in how many lines there are in the file

     // read a line (\n)
    // read the operator(1 or 2) - forget about this one. 3 fscanf
    //scanf first sting; call read int (1st) function
    //same with the second string
    //if 1 then call add, if 2 then call subtract
    // end of loop
    for(i = 0; i < numlines; i++)
    {
        fscanf(fin, "%d", &opr);  // find out whether its add or subtract
        fscanf(fin, "%s", string1); // scan in 2nd number on the first line of input file
            p = read_integer(string1); 
        fscanf(fin, "%s", string2);// scan in 3rd number on the first line of input file
            q = read_integer(string2);
    
        print(p);//call function to print out information
        printf(" ");
        print(q);
        printf("\n");

        if(opr == 1)
        {
         //add
          
          answer = add(p, q);
          print(answer = add(p, q));
        }
        else if(opr == 2)
        {
            printf("subtract here\n");
         // subtract func  
        }
    }
    

        
    fclose(fin);
    system("PAUSE");
    return 0;
}

//Preconditions: the first parameter is string that stores
//               only contains digits, doesn't start with
//               0, and is 200 or fewer characters long.
//Postconditions: The function will read the digits of the
//	large integer character by character, 
//	convert them into integers and return a 
//             pointer to the appropriate struct integer.
struct integer* read_integer(char* stringInt)
{
    int len;
    struct integer *myString;//create a new struct
    int i;//loop index
    //allocate memory for the struct
    myString = (struct integer*)(malloc(sizeof(struct integer)));
    
    len = strlen(stringInt); // length of the strinInt in digits
    
    myString->size = len; // length of string assigned to size in struct myString
    
    //allocate memory for digits
    myString->digits = (int*)(malloc(sizeof(int)* len));
    
    // assign number to digits, convert to integers
    for(i = 0; i < len; i++)
    {
        myString->digits[i] = stringInt [len-1-i] - '0';
    }
    return myString;
}

//Preconditions: p is a pointer to a big integer.
//Postconditions: The big integer pointed to by p is 
//                printed out.
void print(struct integer *p)
{
//given pointer, want to print out digits in reverse order...
    int i;
    // no reversing in add or subtract, but want to reverse here
    for(i = p->size-1; i >= 0; i--)
    {
        printf("%d", p->digits[i]);
    }
    
}
//Preconditions: p and q are pointers to struct integers.
//Postconditions: A new struct integer is created that 
//                stores the sum of the integers pointed to 
//                by p and q and a pointer to it is 
//                returned.
struct integer* add(struct integer *p, struct integer *q)
{
    int i;
    struct integer *addAnsw; //create new struct for answer
    
    //Allocate memory for the new struct
    addAnsw = (struct integer*)(malloc(sizeof(struct integer)));
    
    //Allocate memory for the digits in the new struct addAnsw
    addAnsw->digits = (int*)(malloc(sizeof(int)* (p->size)));
    
  for(i = 1;i <2 i++)
    {
        printf("%d + %d = %d\n", p->digits[i], q->digits[i], addAnsw->digits[i]);
         addAnsw->digits[i] = p->digits[i] + q->digits[i];
    }
    
    return addAnsw;
}

//Preconditions: p and q are pointers to struct integers.
//Postconditions: A new struct integer is created that 
//                stores the absolute value of the 
//                difference between the two and a pointer 
//                to this is returned.
struct integer* subtract(struct integer *p, struct integer *q)
{
       struct integer *subtractAnsw;
       
      //Allocate memory for the new struct
      subtractAnsw = (struct integer*)(malloc(sizeof(struct integer)));
      
       if(p->size < q->size)
       {
            subtractAnsw->digits = (int*)(malloc(sizeof(int)*(p->size)));
       }   
}

//Preconditions: Both parameters of the function are 
//	  pointers to struct integer. 
//Postconditions: The function compares the digits of two 
//	numbers and returns: 
//    -1 if the first number is smaller than the second, 
//     0 if the first number is equal to the second number,
//   1 if the first number is greater than the second.

ok but that doesnt help with the add answer..

What has you confused about adding the two digits? I don't understand.

it wont print out the numbers correctly,